This invention relates to a chair with an adjustable lumbar mechanism, and more specifically, to an improved mechanism which incorporates therein a lumbar member for supporting the lumbar region of the back and a mechanism for adjusting the vertical height thereof.
Typical chairs for use in an office or other environment commonly include various positional features for the comfort of the user. With respect to backrest designs of conventional chairs, lumbar arrangements have been developed to support the natural curve of the spine in order to relieve or minimize stress on the lumbar vertebrae.
One mechanism of the type described above is disclosed in U.S. Pat. No. 5,975,632, which illustrates a chair including a lumbar support incorporated into the back and positioned behind an outer foam layer thereof. The vertical location of the lumbar support is adjustable via a slidable handle disposed adjacent the lower end of the back. A resilient lever-like tongue is cantilevered from the handle and defines a detent adjacent the free end thereof, and when the handle is moved up or down by the user, the detent engages within a selected one of a plurality of recesses disposed along an elongate spine of the back which is fixed to the seat assembly of the chair. In addition, the lumbar member is positively attached via fasteners to the upper end of the handle for movement therewith. In this mechanism, the cantilevered spring force of the tongue can result in upward and downward manual actuation forces which are inconsistent or different from one another. These unbalanced actuation forces tend to make adjustment of the lumbar support by a seated occupant less desirable. Further, the fixed attachment of the lumbar member to the handle by fasteners also complicates assembly.
Accordingly, it is an object of the invention to provide a chair incorporating therein a lumbar member which is easily vertically adjustable by the user, and which provides a simplified attachment of the lumbar member to the slide assembly.
More specifically, one aspect of the invention relates to a chair having a base and a support arrangement mounted on the base which includes back and seat assemblies. The back assembly includes a rigid back support member, and a bracket interconnects the seat and back assemblies. An adjustable lumbar arrangement is associated with the back assembly and includes a lumbar support and a slide element. The lumbar support is mounted on the slide element via a non-fixed connection, and the chair covering or upholstery which is snugly engaged over the back assembly maintains the lumbar support and slide element in engagement with one another.
Further, according to another aspect of the invention, a detent mechanism is provided and cooperates between the bracket and the slide element to adjust the vertical height of the lumbar support relative to the back support member. The detent mechanism is such that the manual actuation forces required to release the detent mechanism to move the lumbar support either upwardly or downwardly are substantially equal to one another, and thus the user does not experience an inconsistency in the amount of force necessary to adjust the lumbar support in one direction versus the other.
Other objects and purposes of the invention will be apparent to persons familiar with structures of this general type upon reading the following specification and inspecting the accompanying drawings.